P804

[plohl]

The billet block was obviously a joke, rather than something requiring and actual discussion. It's probably distracting you from getting your car ready for the mx5 challange....

[greenMachine]

Damn! I wrote a post last night, but it's not here

I think you have probably made the right decision - you are capitalising on your investment (time, money, knowledge), and you would not get that investment back in a sale price of the car.

As far as suggestions go, I would be looking at the brakes (alloy callipers, hats) and the smallest rotors I could get away with. Offset the small rotors with very high temperature pads, and do fast lap/cool down lap/fast lap sessions. Ditch the handbrake if the rules allow, alloy muffler, alloy boot floor. Invest in a good hole saw, and attack all the heavy steel sections of the chassis - with a certain amount of care for strength, but a well designed cage can be useful here, given you need a cage anyway - space frame MX5? V8roadster K-mount (or similar) would save a lot of weight.

Go the Magpie!!

[SKYHI]

804,I'm assuming that this is applying the extra 10% for an Naturally Aspirated car on the listed MX5 NA weight

Ah yes, I forgot about the concession for NA cars. Carry on

[Magpie]

As far as suggestions go, I would be looking at the brakes (alloy callipers, hats) and the smallest rotors I could get away with. Offset the small rotors with very high temperature pads, and do fast lap/cool down lap/fast lap sessions. Ditch the handbrake if the rules allow, alloy muffler, alloy boot floor. Invest in a good hole saw, and attack all the heavy steel sections of the chassis - with a certain amount of care for strength, but a well designed cage can be useful here, given you need a cage anyway - space frame MX5?

Speaking of the hand brake, the cables alone weight 1kg (found out yesterday), also removing the mechanical parts from the rear brakes for the hand brake is not hard.

Space frame - not allowed in clubsprint

However, has anybody considered turning the sills into either ducting or using the channel air out of the front wheel well? Some savings and possible aero advantage...

[16bit]

this may be of interest.

https://forum.miata.net/vb/showthread.php?t=349151

[Magpie]

this may be of interest.

https://forum.miata.net/vb/showthread.php?t=349151

thanks

[greenMachine]

this may be of interest.

https://forum.miata.net/vb/showthread.php?t=349151

and the Where to remove weight from a track only car? sticky from MTnet (only 400 posts ... )

As a track car, structural steel behind the rear subframe mounts and in front of the K-mount is all redundant - all you need is enough strength to mount the panels/garnish/nosecone, and of course the wing/splitter.

[Magpie]

As a track car, structural steel behind the rear subframe mounts and in front of the K-mount is all redundant - all you need is enough strength to mount the panels/garnish/nosecone, and of course the wing/splitter.

Now that is interesting... Time to check the rules. I cannot have a fully tubular construction or composite monocoques and I have to retain the original firewall. The key here could be 'FULLY' tubular, could be partial...

DSCN9885 by Eipeip, on Flickr

DSCN9887 by Eipeip, on Flickr

Found in the drain tubes
DSCN9880 by Eipeip, on Flickr

Yes a 5c piece
DSCN9881 by Eipeip, on Flickr

Could see some of the front brace being replaced/removed
DSCN9889 by Eipeip, on Flickr

All this can be removed to allow the cage to be fitted "Modifications can be made to the firewall for transmission clearance, wiring or roll cage"
DSCN9890 by Eipeip, on Flickr

Only need the hardtop mounts, rest can be removed to facilitate the cage
DSCN9897 by Eipeip, on Flickr

[Magpie]

A relaxing day, 8.3 kgs removed from the shell.

DSCN9907 by Eipeip, on Flickr

The old jack stand zone now has daylight.
DSCN9925 by Eipeip, on Flickr

My helpers for the day
DSCN9926 by Eipeip, on Flickr

[SKYHI]

I assume you've seen how they remove the front crash beam and replace it with a small tube to help with ducting?

[Alex 2550]

hi Magpie,
sounds awesome!!
im very interested in seeing how this turns out, as i have owned quite a few rotors i would love to see one in the front of this thing, the 26B from memory weighs in about 180kg and i believe that was with webbers fitted but certainly don't quote me. i wonder if you would see any displacement penalty for running a rotary? if so 20B may be an option.
i have never been in a quad rotor but looked at a few, i have been in a couple 20B powered cars and going off that the 26 should be silky smooth power.
as for tube front i saw this sometime ago

http://www.speedhunters.com/2017/07/bre ... zda-miata/

it has a tube front however it looks to be heavy but it is supporting an LS3, i more so thought it may give you ideas and its always good to see how others have done it, of course this all hinges on if you can have the tube front.

best of luck with it all mate.
804kg + 26B + your knowledge on the NA chassis would = amazing!

[bruce]

He is using his existing running gear.
Cannot imagine the cost of popping in a rotary, especially a 26B.

[Tim_cyc03]

For the front, just drill the spot welds out and you can remove that whole section with ease, and since it is destine for time attack, I would not put anything in to replace it.

[Magpie]

Keep the suggestions links coming. Have sent an email off to the rule makers to ask what cannot be done. Have started to ask for quotes for a CAMS cage. Suggestions appreciated as well.

I assume you've seen how they remove the front crash beam and replace it with a small tube to help with ducting?

Not seen it but as I imagined it, thanks!

He is using his existing running gear. Cannot imagine the cost of popping in a rotary, especially a 26B.

CORRECT!

For the front, just drill the spot welds out and you can remove that whole section with ease, and since it is destine for time attack, I would not put anything in to replace it.

Done... need to tidy it up.

DSCN9916 by Eipeip, on Flickr

DSCN9912 by Eipeip, on Flickr

This is what I am thinking for the doors. "To fit the cage and to make egress safer, the windows had to be removed to fit the cage. Hence why lexan windows were needed"

[madjak]

Ok you guys aren't thinking through the rule set. You need to be a bit more creative and find the loop holes.

You can remove metal for wheel clearance. In a NA that means the entire inner tub of you setup the ride height low enough. Ideally run 17s with drop spindles for optimal metal removal.

You can also remove metal for cooling, so everything in front of the shock towers can go to alow airflow through the backs of the guards. Maybe some stuff behind the shock tower too to get a bit more airflow. Much better to be safe than sorry when it comes to cooling. There should really just be a couple of tubes hitting the shock towers and the chassis rails in front of the firewall.

You can also remove a whole stack of metal at the back for a diff cooler. Just find the largest and lightest aircon radiator and mount it in the spot where the metal is thickest... and of coarse you have to duct the airflow to it so you can remove pretty much the entire boot floor and rails etc. You might also need to duct it in/out the sides too. You do know mx5s need big diff coolers right?

The heaviest part of a mx5 is the sills. There are two thick metal plates pressed into the middle. That happens to be right where you need to run the lower bar for your cage... what a shame! In fact the whole cage seems to fit best right where all the heavy bits are so better start chopping.

If you design the cage, cooling, fuel tank, seating right you shouldn't have much original car left. I think 804 is easy to hit. No CF required.